This isn't the lowering pass you want. Most GPUs that can support GLSL 1.30 have a multiply unit that can do something more interesting than 32x32->32. Many have 32x16->48. Any GPU that does, should do the lowering in the backend. This is just the thing that will always work. Signed-off-by: Ian Romanick <ian.d.romanick@intel.com> Reviewed-by: Matt Turner <mattst88@gmail.com>